The use of preparative centrifugal stratification chromatography for separating components of a mixture is known (Z. Deyl, J. Rosmus and M. Pavlicek, Chromatogr. Rev. 6 (1964) 19; E. Heftmann, J. M. Krochta, D. F. Farkas and S. Schwimmer, J. Chromatogr. 66 (1972) 365). This method is suitable for separating natural substances (K. Hostettmann, M. Hostettmann-Kaldas and 0. Sticher, J. Chromatogr. 202 (1980) 154; I. R. Hunter, E. Heftmann, J. Liq. Chromatogr. 6 (1983) 281) and technical or synthetic substances (S. Sekiya, K. Tsuji and M. Yamanaka, Yukagaku 28 (1979) 497; S. Chen and J. Wang, Huaxue Tongbao 10 (1982) 591; F. Derguini, V. Balogh-Nair and K. Nakanishi, Tetrahedron Lett. (1979) (4899).
Difficult separations such as, for example, mixtures with several isomers or complex natural substance mixtures have so far not yet been described in the literature. Certain separation problems can be solved only in several separation steps (C. A. J. Erdelmeier, PH.D. Thesis, ETH Zuerich, No. 2794 (1983).
An apparatus has been known since 1979 (U.S. Pat. No. 4,139,458) which makes possible a centrifugal force which is sufficient for the separations, and also a continuous collection of the separated components, and the manufacture of plates with an all-over constant stratification thickness. The apparatus moreover permits preparative separations on a larger scale (several 100s mg.).
The disadvantage of the present preparative centrifugal stratification chromatography methods and apparatuses is that the capacity and the separation performance, when compared with automatically manufactured thin-layer plates, are generally not sufficient.
The horizontal stratification chromatography makes possible, in contrast to vertical stratification chromatography, a practically linear speed of the eluent, but it does not permit a preparative method of operation without cleaning out of substance zones.
During recent years, a new thin-layer chromatography technique, sequential thin-layer chromatography, has been described as an analytical method (P. Buncak, GIT, Supplement Chromatography (1982) 3; U. Klemm, GIT, Supplement Chromatography (1982) (9). This technique is also based on a horizontal development, that is, it works with a practically linear speed of the eluent.
In the sequential thin-layer chromatography, the flow medium is supplied linearly and the supplying can be varied, in parallel, locally and over time. In this method, the flow medium is conveyed exclusively with the help of the capillary action. It is thus possible to improve stages of a total chromatogram in their separation, by choosing the optimum flow medium composition for these separation problems. However, this method cannot be used for preparative purposes without cleaning out and elution of substance zones.